Epilepsy Surgery

Epilepsy surgery involves the surgical removal or disruption of the brain region where seizures originate. This approach is particularly effective for patients with localized seizure foci and can lead to a significant reduction in seizures for many individuals. Surgical intervention provides a long-term solution for patients who are resistant to medication, greatly improving their quality of life.

Brain Anatomy and Epilepsy

Epileptic seizures are caused by abnormal electrical activity in the brain. This electrical activity can originate in a specific region of the brain and spread throughout. The structure and functions of different parts of the brain play a critical role in epilepsy surgery. Surgical intervention requires accurately identifying the region where seizures begin and ensuring the preservation of brain functions while removing the seizure focus.

Structure and Function of the Brain

The brain is an incredibly complex organ composed of different regions, each responsible for specific functions. Epileptic seizures often originate in a specific brain region (seizure focus), and the structure and function of that region determine the characteristics of the seizures. The key regions of the brain are:

• Frontal lobe: Responsible for movement, problem-solving, memory, and emotional regulation. Seizures originating in the frontal lobe can present as sudden movements, muscle contractions, and loss of consciousness.
• Temporal lobe: Handles sensory functions, memory, and speech. Temporal lobe seizures are characterized by sensory hallucinations, déjà vu sensations, and loss of consciousness.
• Parietal lobe: Processes sensory information such as touch, temperature, and pressure. Seizures originating in this region are associated with sensory disturbances.
• Occipital lobe: Processes visual information. Occipital lobe seizures can result in visual hallucinations.

Physiological Processes of Epileptic Seizures

Epileptic seizures occur due to disruptions in normal electrical communication between neurons in the brain. This abnormal electrical activity begins with the hyperexcitability of neurons, which can spread within the brain. Normally, the brain’s electrical activity follows a specific pattern, enabling orderly communication that supports consciousness, movement, sensory perception, and other cognitive functions. However, in epilepsy, this electrical communication becomes disorganized, resulting in seizures.

Importance of Seizure Foci

Identifying the precise region where seizures originate is the most critical factor in determining eligibility for epilepsy surgery. Seizure foci are often identified using neuroimaging techniques such as brain MRI and EEG. The goal of surgical intervention is to remove the seizure focus or disrupt its electrical activity. Temporal lobe epilepsy is the most common type of epilepsy that can be effectively treated through surgical methods.

Process Leading to Epilepsy Surgery

The decision to proceed with epilepsy surgery is a critical and significant step for patients who do not respond to medication. The surgical decision-making process requires detailed evaluation and a multidisciplinary approach. Patients who are candidates for epilepsy surgery must undergo a series of tests to ensure that their seizures can be controlled through surgical intervention.

Diagnosis and Evaluation Process

Epilepsy surgery is the most suitable treatment option for patients with drug-resistant epilepsy. Before making a surgical decision, a multidisciplinary team carefully evaluates the patient’s condition. This team typically includes neurologists, neuropsychologists, radiologists, and neurosurgeons. The following steps are taken to determine whether the patient is suitable for surgery:

• Failure of medication therapy: The first step is to document that the patient’s seizures cannot be controlled with at least two different antiepileptic drugs. If medication is insufficient, surgical intervention becomes an option.
• Seizure frequency and severity: During the surgical decision-making process, the frequency, severity, and impact of seizures on the patient’s quality of life are evaluated. Surgical intervention is appropriate for patients experiencing severe seizures that significantly limit their daily activities.

Diagnostic Tests and Imaging Methods

Before deciding on epilepsy surgery, a series of diagnostic tests and imaging methods are employed to precisely identify the seizure focus. These tests are essential for understanding the region of the brain where seizures originate and planning surgical intervention.

• Electroencephalogram (EEG): EEG measures the brain’s electrical activity and is used to identify the brain region where seizures originate. Abnormal electrical activity in the seizure focus can be detected using electrodes placed on the brain.
• Magnetic Resonance Imaging (MRI): MRI is used to detect structural abnormalities in the brain. Tumors, scar tissue, or structural irregularities in the brain may trigger seizures. MRI provides a clear image of these structural abnormalities.
• Advanced Imaging Techniques: Advanced imaging methods such as PET, SPECT, and MEG help more accurately determine the seizure focus. These techniques reveal metabolic activity in the brain and show which regions are more active during seizures. These methods are particularly important in complex cases.

Types of Epilepsy Surgery

Epilepsy surgery is performed using different methods based on the source of the seizures in the brain and the suitability of that source for surgical intervention. Surgical techniques include removal of seizure foci (resective surgery), regulation of brain functions (stimulation therapies), or interruption of seizure spread (disconnection surgeries). The type of surgery is carefully selected based on each patient’s condition.

Resective Surgery

Resective surgery is one of the most commonly used methods in epilepsy surgery. This type of surgery involves the surgical removal of the abnormal brain region where seizures originate. It is typically preferred when seizures originate from a single focus and do not spread to other parts of the brain.

Temporal Lobectomy

• Definition: Temporal lobe epilepsy is the most common type of epilepsy in which seizures originate in the temporal lobe. Temporal lobectomy involves the surgical treatment of seizures originating from this region.
• How is it performed?: The surgeon removes the affected temporal lobe where abnormal electrical activity originates. During the procedure, neuromonitoring techniques may be used to preserve brain functions. Temporal lobectomy is one of the most successful surgical methods for controlling seizures.
• Success rates: After temporal lobectomy, 70-90% of patients experience a significant reduction in seizures, and some become completely seizure-free. However, some side effects related to the functions of the temporal lobe, such as memory and language impairments, may occur post-surgery.

Frontal Lobectomy

• Definition: Frontal lobe epilepsy is another type of epilepsy in which seizures originate from the frontal lobe. Frontal lobectomy is performed in cases where seizures originate from the frontal lobe and do not respond to medication therapy.
• How is it performed?: The part of the frontal lobe causing the seizures is surgically removed. Since the frontal lobe has numerous cognitive and motor functions, this type of surgery can be more complex and may involve potential side effects, including loss of motor control.
• Success rates: The success rate of frontal lobectomy is typically around 50-70%. However, seizures originating from the frontal lobe have a higher likelihood of recurring after surgery compared to seizures from other lobes.

Parietal and Occipital Lobectomies

• Parietal lobe epilepsy: Although less common, seizures originating from the parietal lobe can be treated surgically. The parietal lobe is responsible for sensory perception and spatial awareness, so surgical risks include sensory impairments.
• Occipital lobe epilepsy: Seizures originating from the occipital lobe, which houses the visual processing center, may pose risks of visual disturbances. However, resective surgery can effectively treat such seizures.

Disconnection Surgeries

Disconnection surgeries aim to prevent the spread of seizures from one brain region to another. These procedures are particularly preferred in cases where seizures involve large areas of the brain.

Corpus Callosotomy

• Definition: The corpus callosum is the main connection pathway between the two hemispheres of the brain. This surgery involves partially or completely severing the corpus callosum to prevent the spread of seizures from one hemisphere to the other.
• How is it performed?: The surgeon cuts the part of the corpus callosum responsible for the spread of seizures, thereby blocking electrical communication between the two brain hemispheres. This procedure is effective in reducing the frequency and severity of seizures, but it does not typically eliminate them entirely.
• Who is it suitable for?: Corpus callosotomy is commonly used in children who experience very severe and widespread seizures, particularly drop attacks (sudden seizure-induced falls).

Hemispherectomy

• Definition: Hemispherectomy is a last-resort surgery used in cases where one hemisphere of the brain is severely damaged and the seizures originate from that hemisphere. The affected hemisphere is either completely removed or rendered nonfunctional.
• How is it performed?: The surgeon removes or disables the damaged hemisphere of the brain. This procedure is usually performed on children because the high plasticity of a young brain allows the other hemisphere to partially compensate for the lost functions.
• Success rates: Hemispherectomy provides 80-90% seizure control in severe and drug-resistant epilepsy cases. However, side effects such as motor function loss and cognitive deficits may occur post-surgery.

Functional Surgery

Functional surgery aims to control seizures without fully disrupting brain functions. These surgeries typically focus on stimulating nerves or blocking seizure signals rather than removing brain tissue.

Vagus Nerve Stimulation (VNS)

• Definition: VNS is a continuous nerve stimulation method that uses a device implanted on the vagus nerve to control seizures. The vagus nerve is one of the key nerves connecting the brain and body, and nerve stimulation can reduce the frequency and severity of seizures.
• How is it performed?: A vagus nerve stimulator is surgically implanted in the chest area and connected to the vagus nerve via wires. The device provides periodic nerve stimulation to suppress seizures.
• Success rates: VNS provides a significant reduction in seizure frequency for approximately 30-50% of patients. It is typically used as an adjunct to medication therapy and does not completely eliminate seizures but can improve patients' quality of life.

Deep Brain Stimulation (DBS)

• Definition: DBS is a newer method in epilepsy treatment that involves continuous electrical stimulation delivered to specific regions of the brain through implanted electrodes.
• How is it performed?: Electrodes are surgically implanted into deep brain regions, and these electrodes are stimulated at regular intervals via a stimulator device. This method can reduce the frequency and severity of seizures.
• Success rates: DBS can be effective for drug-resistant epilepsy patients who are not candidates for resective surgery. However, this method is not yet widely adopted, and further research is ongoing to assess its efficacy.

Steps of Epilepsy Surgery

Epilepsy surgery is meticulously planned and conducted by a multidisciplinary team. This process involves preoperative preparation, surgical intervention, and postoperative recovery stages. At each stage, the patient’s overall health, seizure history, and expectations from surgery are taken into account.

Preoperative Preparation

Epilepsy surgery is a significant decision for the patient and requires a thorough preparation process. This includes determining the patient’s suitability for surgery, precisely localizing seizure foci, and informing the patient and their family about the surgical procedure.

• Diagnosis and Evaluation: A comprehensive diagnostic and evaluation process is necessary to determine surgical eligibility. EEG, MRI, and other imaging techniques are used to precisely locate seizure foci. The patient’s overall health, brain functions, and surgical risks are carefully considered.
• Patient and Family Education: Before surgery, the patient and their family are informed in detail about the risks, success rates, and potential side effects of the procedure. The goals of the surgery, expectations, and long-term outcomes are discussed.

Surgical Process

Epilepsy surgery is performed to either remove seizure foci or prevent seizure propagation. Advanced neuromonitoring techniques are used during surgery to preserve brain functions.

• Surgical Steps: During the procedure, seizure foci are removed, or neural pathways are blocked with minimal damage to brain tissue. Surgeons continuously monitor the patient’s motor and cognitive functions throughout the operation.
• Neuromonitoring: Neuromonitoring is conducted to protect critical brain regions responsible for essential functions. This ensures that the patient remains conscious during the surgery and that brain functions are not compromised by the intervention.

Postoperative Recovery

The recovery process following epilepsy surgery can vary from patient to patient. During recovery, seizure control, healing of the surgical site, and monitoring of potential side effects are prioritized.

• Seizure Monitoring: After surgery, the frequency and severity of seizures are closely monitored. Some patients may become completely seizure-free, while others may experience a significant reduction in seizure frequency.
• Physical and Cognitive Rehabilitation: Some patients may experience motor or cognitive function loss following surgery. In such cases, physical therapy and rehabilitation programs are implemented. Neuropsychological evaluation and therapy may be required to maintain or recover cognitive functions.

Success Rates and Risks of Epilepsy Surgery

Epilepsy surgery is a highly effective treatment option for patients with drug-resistant epilepsy. However, like all surgical interventions, the success rates and potential risks of epilepsy surgery can vary depending on the patient. Success rates are influenced by the type of surgery, the origin of the seizures, and the patient's overall health, while risks depend on the brain region being operated on and the surgical method used.

Success Rates

Epilepsy surgery demonstrates high success rates in achieving seizure control in eligible patients. The success rates vary between surgical methods. Resective surgeries, which involve the removal of specific brain regions where seizures originate, show particularly high success rates.

• Temporal Lobectomy Success Rates
  • Temporal lobectomy is one of the most commonly performed epilepsy surgeries and has high success rates. Approximately 70-90% of patients who undergo temporal lobectomy experience a significant reduction in seizures, and about 60% of patients remain completely seizure-free after the procedure.
  • Long-term outcomes: In successful cases, patients may experience years without seizures and a significant improvement in quality of life. However, seizures may recur in some patients a few years after the surgery.
• Frontal Lobectomy and Other Resective Surgeries
  • Frontal lobectomy achieves a success rate of 50-70% in treating seizures originating from the frontal lobe. Due to the complex nature of frontal lobe seizures, this surgery has slightly lower success rates compared to other lobes. Nonetheless, significant reductions in seizure frequency and severity can be achieved.
  • Parietal and Occipital Lobectomies: While less common, these surgeries achieve success rates of 60-70% in cases where seizures are localized.
• Disconnection Surgery Success Rates
  • Corpus callosotomy aims to prevent the spread of seizures between brain hemispheres. Success rates depend on the type of seizures, but it is particularly effective in cases of drop attacks. Corpus callosotomy generally reduces the severity and frequency of seizures rather than eliminating them entirely. Approximately 50-70% of patients experience a significant reduction in seizure frequency.
  • Hemispherectomy: This procedure is performed in children with severe and widespread seizures and achieves seizure control in 80-90% of cases. However, due to the potential for significant side effects, it is considered a last-resort treatment.
• Success Rates of Functional Surgeries
  • Vagus Nerve Stimulation (VNS): While this method does not completely eliminate seizures, it achieves a significant reduction in seizure frequency in approximately 30-50% of patients. VNS is usually combined with medication therapy and helps improve the quality of life for patients.
  • Deep Brain Stimulation (DBS): DBS improves seizure control in up to 50% of patients. It is particularly effective in drug-resistant epilepsy patients, but more research is needed to evaluate its long-term outcomes.

Surgical Risks and Potential Complications

Like all surgical interventions, epilepsy surgery carries certain risks and potential complications. These risks vary depending on the type of surgery, the region of the brain involved, and the patient's overall health. To minimize postoperative complications, the surgery must be carefully planned and performed by experienced surgeons and multidisciplinary teams.

General Surgical Risks

• Bleeding and infection: As with all surgical procedures, epilepsy surgery carries risks of bleeding and infection. These risks are more significant in brain surgery due to the potential for serious complications.
• Brain edema (swelling): Swelling in the brain may occur after surgery, potentially leading to temporary or permanent neurological impairments.
• Post-surgical persistence of seizures: In some patients, seizures may persist even after a successful surgery. While seizure severity may decrease, some patients may still require continued medication.

Loss of Brain Function

• Memory and cognitive impairments: Memory and learning functions may decline, particularly after temporal lobectomy. Since the temporal lobe is closely associated with memory and language functions, such side effects, while rare, may occur.
• Motor function loss: Surgeries involving the frontal or parietal lobes may have adverse effects on movement and motor skills. Patients may require rehabilitation programs following these types of surgeries.
• Sensory loss: Surgeries on the occipital or parietal lobes may result in impairments in sensory functions such as vision or touch.

Post-Surgical Psychological and Social Effects

• Post-surgical stress and anxiety: Patients may experience psychological stress and anxiety after surgery. If seizures are not fully controlled, there may be an increased risk of depression and anxiety.
• Difficulty adapting to social life: Patients may face challenges in adapting to social life after surgery. These issues can often be managed with post-surgical psychological support.

Possibility of Seizure Recurrence Post-Surgery

While epilepsy surgery generally has high success rates, seizures may recur in some patients a few years after surgery. This is especially common in cases of frontal and parietal lobe seizures. The risk of seizure recurrence depends on whether the surgical procedure fully addressed the seizure focus. In cases of recurrence, additional surgical interventions or medication may be required.

Alternative Treatment Options to Surgery

Although epilepsy surgery may be the most effective solution for patients with drug-resistant epilepsy, surgery is not always a viable option. For patients with high surgical risks, alternative treatment methods are explored. These methods can be effective in controlling seizures and provide a solution for patients not suited for surgery.

Medication Therapy

The most common treatment for epilepsy is antiepileptic medication. These drugs aim to prevent seizures by reducing overactivity in brain cells. However, one in three epilepsy patients does not respond to medication, in which case surgery or alternative treatments are considered.

Drug-Resistant Epilepsy

Approximately 30% of epilepsy patients do not respond to antiepileptic drugs. These patients fall into the category of drug-resistant (refractory) epilepsy, where surgical options often become a critical consideration.

Dietary Therapies

The ketogenic diet can be used as an adjunct or alternative treatment for epilepsy. This diet relies on fats as the primary energy source and can effectively reduce seizure frequency.

Ketogenic Diet

The ketogenic diet is primarily used in the treatment of epilepsy in children. By limiting carbohydrate intake and increasing fat consumption, the diet promotes the production of ketones, which serve as an alternative energy source for the brain and can help reduce seizures.

The ketogenic diet has been shown to achieve positive outcomes in 30-40% of patients with drug-resistant epilepsy, helping to control seizures.

Non-Invasive Brain Stimulation

Non-invasive brain stimulation techniques are alternative treatments for epilepsy that do not require surgical intervention. These techniques modulate electrical activity in the brain to reduce seizure frequency and severity. They offer promising options for patients not eligible for or unwilling to undergo surgery.

Transcranial Magnetic Stimulation (TMS)

TMS is a treatment method that uses magnetic pulses to alter the electrical activity of neurons in specific brain regions. It aims to suppress the electrical activity in the brain areas responsible for seizures, thereby reducing seizure frequency.

How it is performed: TMS is applied by placing magnetic coils on the scalp. These coils deliver brief magnetic pulses that penetrate the brain tissue and alter electrical activity in the targeted region.

Success rates: TMS can reduce seizure frequency by 30-50% in epilepsy patients. However, its effectiveness is still being studied, and its long-term outcomes are not yet fully understood.

Transcranial Direct Current Stimulation (tDCS)

tDCS is a treatment method that involves directly stimulating neurons in the brain with electrical current to control seizures. Like TMS, tDCS is a non-invasive technique and is used particularly in drug-resistant epilepsy cases.

How it is applied: In tDCS treatment, low-intensity electrical current is delivered to brain tissue through electrodes placed on the scalp. This method regulates the activity of neurons in the region of the brain where seizures originate.

Success rates: tDCS can be effective in controlling seizures in approximately 20-40% of epilepsy patients. However, further research is needed to evaluate its effectiveness and long-term use.

The Impact of Epilepsy Surgery on Quality of Life

Epilepsy surgery not only effectively controls seizures in patients resistant to medication but also significantly improves their quality of life. By gaining control over seizures, patients experience marked improvements not only in neurological functions but also in their daily activities and social relationships.

Quality of Life Improvement Through Seizure Control

The most significant benefit of epilepsy surgery is the noticeable reduction in seizure frequency and severity. Complete cessation or substantial reduction in seizures after surgery leads to significant quality-of-life improvements for patients. Controlling seizures allows patients to rejoin social and professional life.

Reorganizing Daily Life

Reducing seizures helps patients regain confidence and live independently. Many epilepsy surgery patients gain the freedom to perform previously limited activities, such as driving, working, or pursuing education.

Participation in Work and Social Life

Living seizure-free after surgery enables patients to engage more actively in their professional and social lives. Patients who had lost jobs or faced social isolation due to seizures can return to work and participate more actively in social settings with seizure control.

Psychological and Social Effects

Epilepsy surgery has significant impacts not only on neurological outcomes but also on patients' psychological and social well-being. Controlling seizures can alleviate emotional problems such as anxiety, depression, and social isolation.

Reduction in Depression and Anxiety

Epileptic seizures often bring uncertainty to patients' lives, leading to psychological issues such as anxiety and depression. Controlling seizures reduces these problems. Patients, especially those who achieve complete seizure cessation, often experience increased confidence and emotional well-being.

Improvement in Social Relationships

Epileptic seizures can limit patients' social interactions. Controlling seizures enables patients to participate more freely in social activities. After surgery, patients can lead a more active social life without the fear of seizures.

Post-Surgery Rehabilitation and Support

In the post-surgical period, patients may require physical, cognitive, and psychological rehabilitation programs to fully improve their quality of life. These programs help preserve neurological functions and support patients' adaptation to daily life.

Physical Rehabilitation

Patients experiencing motor function loss after surgery may undergo physical therapy programs. These rehabilitation processes help patients regain motor skills and return to independent living.

Psychological Support

Patients who undergo epilepsy surgery may also benefit from psychological support and counseling services. Psychological support contributes to the recovery process for patients experiencing post-surgical anxiety, depression, or social adaptation challenges.

Innovations and Future Directions in Epilepsy Surgery

Significant advancements have been made in epilepsy surgery in recent years. Improvements in surgical techniques and the development of new treatment approaches provide safer and more effective solutions for epilepsy patients. Future innovations in epilepsy surgery aim to enhance seizure control and reduce surgical risks.

Laser Ablation Therapy

Laser ablation is emerging as a minimally invasive method in epilepsy treatment. This technique involves using lasers to target and destroy seizure foci with minimal damage to brain tissue, aiming to control seizures.

• How it works: In laser ablation therapy, seizure foci are identified using MRI and targeted with lasers. This method destroys epileptic foci by heating them without damaging surrounding brain tissue.
• Advantages: Laser ablation reduces surgical risks due to its minimally invasive nature and accelerates recovery. Additionally, it carries a lower risk of post-operative complications.

Neurofeedback and Brain-Computer Interfaces

Neurofeedback is a method used to detect seizures in advance and regulate brain activity in epilepsy patients. This technique monitors brain waves to detect the onset of seizures and alerts the patient beforehand.

• How it works: Neurofeedback devices monitor brain waves and enable patients to consciously regulate brain activity. This method helps patients maintain control during seizures by detecting them early.
• Future directions: Neurofeedback may become more widely used in epilepsy treatment in the future. Combined with brain-computer interfaces, these technologies represent a significant step forward in improving seizure control for patients.

Genetic and Molecular Therapies

Research on genetic and molecular therapies holds great promise for patients with a genetic predisposition to epilepsy. In particular, gene therapy plays a significant role in addressing the genetic causes of epilepsy.

• Gene therapy: Studies on genetic mutations causing epilepsy aim to correct these mutations through gene therapy. In the future, gene therapy may provide more permanent solutions for genetic epilepsy cases.
• Molecular therapies: Research on molecules that regulate the electrical activity of brain cells also offers hope in epilepsy treatment. These therapies aim to directly target the source of seizures, providing better seizure control for patients.

Conclusion

Epilepsy surgery provides an effective and permanent solution for patients who do not respond to medication. Surgical intervention significantly improves patients' quality of life by greatly reducing the frequency and severity of seizures. However, the success of the procedure depends on the patient’s suitability for surgery, accurate identification of seizure foci, and the meticulous execution of the surgical process.

While epilepsy surgery boasts high success rates in seizure control, surgical risks and potential complications must be considered. Each patient’s case is unique, and the decision for surgical treatment should be carefully evaluated by a multidisciplinary team.

In the future, innovative treatment methods such as laser ablation, neurofeedback, and gene therapy will offer safer and more effective solutions for epilepsy treatment. Determining the most suitable treatment options for epilepsy patients requires an individualized evaluation and a patient-centered approach tailored to specific needs. This way, patients living with epilepsy can achieve a better and seizure-free quality of life.